DOCSLIB.ORG

Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia) geosciences Article Ti-Nb Mineralization of Late Carbonatites and Role of Fluids in Its Formation: Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia) Evgeniy Kozlov 1,* ID , Ekaterina Fomina 1, Mikhail Sidorov 1 and Vladimir Shilovskikh 2 ID 1 Geological Institute, Kola Science Centre, Russian Academy of Sciences, 14, Fersmana Street, 184209 Apatity, Russia; [email protected] (E.F.); [email protected] (M.S.) 2 Resource center for Geo-Environmental Research and Modeling (GEOMODEL), St. Petersburg State University, 1, Ulyanovskaya Street, 198504 Saint Petersburg, Russia; [email protected] * Correspondence: [email protected]; Tel.: +7-953-758-7632 Received: 6 July 2018; Accepted: 25 July 2018; Published: 28 July 2018 Abstract: This article is devoted to the geology of titanium-rich varieties of the Petyayan-Vara rare-earth dolomitic carbonatites in Vuoriyarvi, Northwest Russia. Analogues of these varieties are present in many carbonatite complexes. The aim of this study was to investigate the behavior of high field strength elements during the late stages of carbonatite formation. We conducted a multilateral study of titanium- and niobium-bearing minerals, including a petrographic study, Raman spectroscopy, microprobe determination of chemical composition, and electron backscatter diffraction. Three TiO2-polymorphs (anatase, brookite and rutile) and three pyrochlore group members (hydroxycalcio-, fluorcalcio-, and kenoplumbopyrochlore) were found to coexist in the studied rocks. The formation of these minerals occurred in several stages. First, Nb-poor Ti-oxides were formed in the fluid-permeable zones. The overprinting of this assemblage by residual fluids led to the generation of Nb-rich brookite (the main niobium concentrator in the Petyayan-Vara) and minerals of the pyrochlore group. This process also caused niobium enrichment with of early generations of Ti oxides. Our results indicate abrupt changes in the physicochemical parameters at the late hydro (carbo) thermal stage of the carbonatite formation and high migration capacity of Ti and Nb under these conditions. The metasomatism was accompanied by the separation of these elements. Keywords: metasomatism; brookite; anatase; pyrochlore; niobium; carbonatites; Vuoriyarvi massif 1. Introduction Carbonatites are defined in the International Union of Geological Sciences (IUGS) system of classification as igneous rocks containing more than 50 modal percent carbonate [1]. Varieties of carbonatite are named based on the dominant carbonate mineral [2]. They have been chemically classified according to the percent by mass of CaO, MgO, and FeOT and MnO [1], which has an evolutionary aspect as well. Most of the known carbonatite complexes have a common scheme of carbonatite genesis, whereby early calciocarbonatites were replaced by magnesiocarbonatites, and ferrocarbonatites, as the most recent [3]. The latter are considerably affected by carbo(hydro)thermal-metasomatic processes as they develop [4]. In general, carbonatites account for more than 50% of global rare-earth elements (REE) resources, which include Y and La-Lu [5]. REE enrichment is “most commonly found only in the latest and most highly evolved parts of a carbonatite intrusion” [6]. The accumulation of REE in late carbonatites is assumed to be controlled by fluid activity [7–16]. Such a surplus in articles reflects a keen interest in REE occurring in late carbonatites. More than 99% of the world’s niobium (Nb) is also Geosciences 2018, 8, 281; doi:10.3390/geosciences8080281 www.mdpi.com/journal/geosciences Geosciences 2018, 8, 281 2 of 19 known to be associated with carbonatite complexes [17]. Still, only a limited number of works were dedicated to the behavior of high field strength elements (HFSE), which include Ti, Nb, Ta, Zr, and Hf, regardless of commercial value, at the final stages of the carbonatite genesis. The reason is that HFSE, unlike REE, are thought to be confined to the magmatic stage of the carbonatite genesis [18]. Moreover, a regular decrease in HFSE content occurs from early to late carbonatites [19]. However, this may not exclusively be the case. In most carbonatite deposits, the main niobium concentrators are minerals of the pyrochlore group and, less frequently, the perovskite, columbite, and euxenite groups [17]. The deposits are divided into primary (i.e., primarily magmatic) and secondary. The latter are richer and are supposed to have accumulated Nb minerals and other HFSE, due to their low mobility in the areas of laterite weathering above primary deposits. As such, late carbonatites have a specific HFSE-mineralization. Examples include the industrially valuable deposits of the Magnet Cove complex in the U.S. [20,21], carbonatites of the Salpeterkop complex in South Africa [22], and the Gross Brukkaros complex in Namibia [23]. Nb-rich polymorphs of TiO2 play a key role in all the listed deposits. These minerals (anatase, rutile, and brookite) are also found in many other complexes [24]. They are typomorphic for late carbonatites and reflect the process that completes the picture of late carbonatite petrogenesis. The evolution of the Morro dos Seis Lagos Nb (Ti, REE) deposit (Amazonas, Brazil) deserves particular attention. Here again, the main ore mineral is Nb-rich rutile. Reserves of this deposit are tremendous: they are up to 2.9 billion tons with 2.81 wt % Nb2O5 [25], which is much higher than in the largest known pyrochlore deposit. Hypergenesis certainly played a crucial role in the HFSE concentration process in the Morro dos Seis Lagos. However, laterites in this complex formed after ferro-(siderite)carbonatites that were originally rich in Ti and Nb [25]. In the Seis Lagos, like in many other complexes, Nb-bearing oxides are described as secondary phases replacing originally magmatic pyrochlores, perovskites, and other minerals. Still, this mechanism is not universal for carbonatites. Pseudomorphing of originally magmatic minerals is commonly associated with direct deposition of TiO2 polymorphs from fluids. In the latter case, more Nb often occurs in titanium phases, as described for the Gross Brukkaros [23]. Moreover, some examples have no pseudomorphs of rutile, brookite, or anatase after other phases. Only paramorphs of certain TiO2 modifications have been found, like in the Magnet Cove [26]. This calls into question the existing models of HFSE mineralization in carbonatites. Considering these challenges, decoding the processes of the late carbonatites petrogenesis is a major task. Determining these processes has both practical and fundamental value. The key step in the petrogenetic decoding is applying genetic mineralogy methods to Ti and Nb oxides [23,27–29]. The real challenge is dividing the late metasomatic changes and hypergenesis processes, which obscure earlier processes. The task becomes easier in the Vuoriyarvi. Weathering crusts that existed before the latest glaciations were eroded by glacial abrasion. Subsequently, almost no hypergenesis processes occurred due to the site’s location in the sub-Arctic region [30]. These “preserved” sites help to identify products of late hydrothermal alteration and those of hypergenetic processes [31]. Studying the evolution of the Ti-Nb mineralization in the Petyayan-Vara has supported a high migration capacity at the late hydrothermal stage of such immobile elements as Ti and Nb. We have also found evidence of fluid activity being accompanied by these elements’ fractionation. 2. Geological Setting of the Petyayan-Vara Rocks This research focused on the poorly studied carbonatites of the Petyayan-Vara area at the eastern flank of the Vuoriyarvi alkaline-ultrabasic carbonatite complex, southwest of the Murmansk region, Northwest Russia. The Vuoriyarvi is one of the Devonian Kola Alkaline Province massifs [32]. Its concentrically zonal structure (Figure1) includes almost all rock varieties typical for such massifs [33]. Geosciences 2018, 8, 281 3 of 19 Geosciences 2018, 8, x FOR PEER REVIEW 3 of 19 Figure 1. The geological setting and structure of the Vuoriyarvi alkaline-ultrabasic carbonatite Figure 1. The geological setting and structure of the Vuoriyarvi alkaline-ultrabasic carbonatite complex complex after [33], simplified and added. Blue circles indicate positions of the Tukhta-Vara, Neske- after [33], simplified and added. Blue circles indicate positions of the Tukhta-Vara, Neske-Vara and Vara and Petyayan-Vara carbonatite fields and the Kolvikskiy agpaitic nepheline-syenite massif- Petyayan-Vara carbonatite fields and the Kolvikskiy agpaitic nepheline-syenite massif-satellite. satellite. Thus, at the current erosion section, the massif core is composed of olivitites (the first phase of Thus, at the current erosion section, the massif core is composed of olivitites (the first phase of intrusion) surrounded by pyroxenites (the intermediate ring, second phase) and foidolites (the outer intrusion) surrounded by pyroxenites (the intermediate ring, second phase) and foidolites (the outer ring, third phase). The next (fourth) stage of the magma intrusion produced nepheline syenites and ring, third phase). The next (fourth) stage of the magma intrusion produced nepheline syenites and related rocks concentrated in the Kolvikskiy massif-satellite mostly. The youngest formations of the related rocks concentrated in the Kolvikskiy massif-satellite mostly. The youngest formations of the Vuoriyarvi are stockwork-like bodies of various carbonatites (fifth phase) cutting other rocks and Vuoriyarvi are stockwork-like bodies of various
Load more

Recommended publications
  • 19660017397.Pdf
    .. & METEORITIC RUTILE Peter R. Buseck Departments of Geology and Chemistry Arizona State University Tempe, Arizona Klaus Keil Space Sciences Division National Aeronautics and Space Administration Ames Research Center Mof fett Field, California r ABSTRACT Rutile has not been widely recognized as a meteoritic constituent. show, Recent microscopic and electron microprobe studies however, that Ti02 . is a reasonably widespread phase, albeit in minor amounts. X-ray diffraction studies confirm the Ti02 to be rutile. It was observed in the following meteorites - Allegan, Bondoc, Estherville, Farmington, and Vaca Muerta, The rutile is associated primarily with ilmenite and chromite, in some cases as exsolution lamellae. Accepted for publication by American Mineralogist . Rutile, as a meteoritic phase, is not widely known. In their sunanary . of meteorite mineralogy neither Mason (1962) nor Ramdohr (1963) report rutile as a mineral occurring in meteorites, although Ramdohr did describe a similar phase from the Faxmington meteorite in his list of "unidentified minerals," He suggested (correctly) that his "mineral D" dght be rutile. He also ob- served it in several mesosiderites. The mineral was recently mentioned to occur in Vaca Huerta (Fleischer, et al., 1965) and in Odessa (El Goresy, 1965). We have found rutile in the meteorites Allegan, Bondoc, Estherville, Farming- ton, and Vaca Muerta; although nowhere an abundant phase, it appears to be rather widespread. Of the several meteorites in which it was observed, rutile is the most abundant in the Farmington L-group chondrite. There it occurs in fine lamellae in ilmenite. The ilmenite is only sparsely distributed within the . meteorite although wherever it does occur it is in moderately large clusters - up to 0.5 mn in diameter - and it then is usually associated with chromite as well as rutile (Buseck, et al., 1965), Optically, the rutile has a faintly bluish tinge when viewed in reflected, plane-polarized light with immersion objectives.
    [Show full text]
  • Tundrite-(Ce) Na3(Ce; La)4(Ti; Nb)2(Sio4)2(CO3)3O4(OH) ² 2H2O C 2001 Mineral Data Publishing, Version 1.2 ° Crystal Data: Triclinic
    Tundrite-(Ce) Na3(Ce; La)4(Ti; Nb)2(SiO4)2(CO3)3O4(OH) ² 2H2O c 2001 Mineral Data Publishing, version 1.2 ° Crystal Data: Triclinic. Point Group: 1: Crystals acicular along [001] and °attened on 010 , to 3 cm; as stellate groups and spherulitic masses. Twinning: On 010 , producing f g f g pseudorhombohedra. Physical Properties: Cleavage: Pronounced on 010 . Fracture: Splintery. f g Tenacity: Brittle. Hardness = 3 D(meas.) = 3.70{4.12 D(calc.) = 4.06 » Optical Properties: Transparent. Color: Brownish yellow, greenish yellow to bright light green. Streak: Yellowish gray. Luster: Vitreous to adamantine. Optical Class: Biaxial (+). Pleochroism: Weak; X = pale yellow; Z = greenish yellow. Orientation: Z c = 4 {14 . ® = 1.743 ¯ = 1.80 ° = 1.88 2V(meas.) = 76 ^ ± ± ± Cell Data: Space Group: P 1: a = 7.533(4) b = 13.924(6) c = 5.010(2) ® = 99±52(2)0 ¯ = 70±50(3)0 ° = 100± 59(2)0 Z = 1 X-ray Powder Pattern: Il¶³maussaq intrusion, Greenland. 13.49 (100), 2.505 (100), 3.448 (90), 2.766 (90), 3.535 (80), 6.784 (70), 1.914 (70) Chemistry: (1) SiO2 10.03 TiO2 12.20 La2O3 8.57 Ce2O3 24.38 Nd2O3 10.25 RE2O3 5.80 Nb2O5 3.44 CaO 0.75 Na2O 8.20 CO3 16.38 Total [100.00] (1) Il¶³maussaq intrusion, Greenland; by electron microprobe, C con¯rmed by loss on ignition; original analysis given as elements, here recalculated to oxides, corresponding to Na3:17(Ce1:78Nd0:73La0:63RE0:41Ca0:16)§=3:71(Ti1:83Nb0:31)§=2:14(SiO4)2:00(CO3)3:27O4:25: Occurrence: In pegmatite veins associated with nepheline syenites.
    [Show full text]
  • Washington State Minerals Checklist
    Division of Geology and Earth Resources MS 47007; Olympia, WA 98504-7007 Washington State 360-902-1450; 360-902-1785 fax E-mail: [email protected] Website: http://www.dnr.wa.gov/geology Minerals Checklist Note: Mineral names in parentheses are the preferred species names. Compiled by Raymond Lasmanis o Acanthite o Arsenopalladinite o Bustamite o Clinohumite o Enstatite o Harmotome o Actinolite o Arsenopyrite o Bytownite o Clinoptilolite o Epidesmine (Stilbite) o Hastingsite o Adularia o Arsenosulvanite (Plagioclase) o Clinozoisite o Epidote o Hausmannite (Orthoclase) o Arsenpolybasite o Cairngorm (Quartz) o Cobaltite o Epistilbite o Hedenbergite o Aegirine o Astrophyllite o Calamine o Cochromite o Epsomite o Hedleyite o Aenigmatite o Atacamite (Hemimorphite) o Coffinite o Erionite o Hematite o Aeschynite o Atokite o Calaverite o Columbite o Erythrite o Hemimorphite o Agardite-Y o Augite o Calciohilairite (Ferrocolumbite) o Euchroite o Hercynite o Agate (Quartz) o Aurostibite o Calcite, see also o Conichalcite o Euxenite o Hessite o Aguilarite o Austinite Manganocalcite o Connellite o Euxenite-Y o Heulandite o Aktashite o Onyx o Copiapite o o Autunite o Fairchildite Hexahydrite o Alabandite o Caledonite o Copper o o Awaruite o Famatinite Hibschite o Albite o Cancrinite o Copper-zinc o o Axinite group o Fayalite Hillebrandite o Algodonite o Carnelian (Quartz) o Coquandite o o Azurite o Feldspar group Hisingerite o Allanite o Cassiterite o Cordierite o o Barite o Ferberite Hongshiite o Allanite-Ce o Catapleiite o Corrensite o o Bastnäsite
    [Show full text]
  • Mineral Processing
    Mineral Processing Foundations of theory and practice of minerallurgy 1st English edition JAN DRZYMALA, C. Eng., Ph.D., D.Sc. Member of the Polish Mineral Processing Society Wroclaw University of Technology 2007 Translation: J. Drzymala, A. Swatek Reviewer: A. Luszczkiewicz Published as supplied by the author ©Copyright by Jan Drzymala, Wroclaw 2007 Computer typesetting: Danuta Szyszka Cover design: Danuta Szyszka Cover photo: Sebastian Bożek Oficyna Wydawnicza Politechniki Wrocławskiej Wybrzeze Wyspianskiego 27 50-370 Wroclaw Any part of this publication can be used in any form by any means provided that the usage is acknowledged by the citation: Drzymala, J., Mineral Processing, Foundations of theory and practice of minerallurgy, Oficyna Wydawnicza PWr., 2007, www.ig.pwr.wroc.pl/minproc ISBN 978-83-7493-362-9 Contents Introduction ....................................................................................................................9 Part I Introduction to mineral processing .....................................................................13 1. From the Big Bang to mineral processing................................................................14 1.1. The formation of matter ...................................................................................14 1.2. Elementary particles.........................................................................................16 1.3. Molecules .........................................................................................................18 1.4. Solids................................................................................................................19
    [Show full text]
  • Mineral to Metal: Processing of Titaniferous Ore to Synthetic Rutile (Tio2) and Ti Metal
    Mineral to Metal: Processing of Titaniferous Ore to Synthetic Rutile (TiO2) and Ti metal Dr Jeya Ephraim, Mineral to Metal May 11 – 13, 2015 * Hilton Birmingham Metropole Hotel * Birmingham, United Kingdom Objective To produce ultra pure high grade synthetic rutile (TiO2) from ilmenite ore and Ti metal from anatase or rutile Dr Jeya Ephraim, Mineral to Metal May 11 – 13, 2015 * Hilton Birmingham Metropole Hotel * Birmingham, United Kingdom Outline 1. Introduction 2. Why titaniferous minerals? 3. Processing Methods for synthetic rutile (TiO2) (i) Alkali Roasting (ii) Reduction followed by leaching 5. Results and discussion 6. Commercialisation 7. Conclusion 8. Bradford Metallurgy on Ti metal powder production 9. Future Plans Dr Jeya Ephraim, Mineral to Metal May 11 – 13, 2015 * Hilton Birmingham Metropole Hotel * Birmingham, United Kingdom Introduction • Titanium always exist as bonded to other elements in nature. • It is the ninth-most abundant element in the Earth. • It is widely distributed and occurs primarily in the minerals such as anatase, brookite, ilmenite, perovskite, rutile and titanite (sphene). • Among these minerals, only rutile and ilmenite have economic importance Dr Jeya Ephraim, Mineral to Metal May 11 – 13, 2015 * Hilton Birmingham Metropole Hotel * Birmingham, United Kingdom Ilmenite deposit in Chavara, Kerala, India Dr Jeya Ephraim, Mineral to Metal May 11 – 13, 2015 * Hilton Birmingham Metropole Hotel * Birmingham, United Kingdom Applications of TiO2 • White powder pigment - brightness and very high refractive index - Sunscreens use TiO2 - high refractive index - protect the skin from UV light. • TiO2 – photocatalysts - electrolytic splitting of water into hydrogen and oxygen, - produce electricity in nanoparticle form -light-emitting diodes, etc.
    [Show full text]
  • First Terrestrial Occurrence of Titanium
    875 Thz Caradian M fuc ralo g is t Vol.35, pp. 875-885(1997) FIRSTTERRESTRIAL OCCURRENCE OF TITANIUM.RICH PYRRHOTITE, MARCASITEAND PVRITEIN A FENITIZEDXENOLITH FROMTHE KHIBINA ALKALINE COMPLEX. RUSSIA ANDREI Y. BARKOVT nxp KAUKO V.O. LAAJOKI Irxtiruteof Geosciencesand Astrorcmy, University of Oula FIN-90570OuIW FinLand YT]RIP.MEN'SHIKOV Geological Instirute, Kola Science Cente, Russian Acadenry of Scimces, 14 Fersman Street, Apatity 1M200 , Russia TUOMO T. AI.APIETI Instituteof Geoscierrcesand Astrotnnry, University of Ouh+FN-90570 OuIu Finlnnl SEPPOJ. SryONEN Instiarcof ElcctronOptics, University of OuhaFN-90570 Ouh+ Finlnnd ABSTRACT The first terrestrial titanium-rich sulfides, the fust natural niobium-rich sulfide FeMgSe, fluorine-rich (ca. 6 wt.Vo D end-memberphlogopite (S().04 wLTo FeO) and ferroan alabandite occurlocally in aheterogeneous xenolit\ enclosed within nepheline syenite in the l(hifiaa alkalins gs6plex, Kola Peninsul4 northwestem Russia- This assemblage is exclusively associated with an alkali-feldspar-rich rock, probably fenite. Associat€d ninerals include corundum, Nb-Zr-bearing rutile and monazite. The maximum Ti content reaches 3.9 w.7o in pynhotite and 2 wt.7o in marcasite and pyrite, which represent prducts of replacement of the pynhotite. Titanium is distributed rather homogeneously within single grains of the pyrrhotite; however, a strong grain-to-gain variation is observed. The Tl-rich sulfides invariably contrin an elevated level ofvanadium (0.2-0 .4 wr.Vo).T\e results indicate that both Ti and V enter into solid solution in the sulfides. Presumably, there is an environmental similarity between the occurrences ofTl-bearing sulfides in trftibina and in meteorites (enstatite chondrites), where Tl-bearing hoilite occurs.
    [Show full text]
  • Zirconolite, Chevkinite and Other Rare Earth Minerals from Nepheline Syenites and Peralkaline Granites and Syenites of the Chilwa Alkaline Province, Malawi
    Zirconolite, chevkinite and other rare earth minerals from nepheline syenites and peralkaline granites and syenites of the Chilwa Alkaline Province, Malawi R. G. PLATT Dept. of Geology, Lakehead University, Thunder Bay, Ontario, Canada F. WALL, C. T. WILLIAMS AND A. R. WOOLLEY Dept. of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD, U.K. Abstract Five rare earth-bearing minerals found in rocks of the Chilwa Alkaline Province, Malawi, are described. Zirconolite, occurring in nepheline syenite, is unusual in being optically zoned, and microprobe analyses indicate a correlation of this zoning with variations in Si, Ca, Sr, Th, U, Fe, Nb and probably water; it is argued that this zoning is a hydration effect. A second compositional zoning pattern, neither detectable optically nor affected by the hydration, is indicated by variations in Th, Ce and Y such that, although total REE abundances are similar throughout, there appears to have been REE fractionation during zirconolite growth from relatively heavy-REE and Th-enrichment in crystal cores to light-REE enrichment in crystal rims. Chevkinite is an abundant mineral in the large granite quartz syenite complexes of Zomba and Mulanje, and analyses are given of chevkinites from these localities. There is little variation in composition within each complex, and only slight differences between them; they are all typically light-REE-enriched. The Mulanje material was shown by X-ray diffraction to be chevkinite and not the dimorph perrierite, but chemical arguments are used in considering the Zomba material to be the same species. Other rare earth minerals identified are monazite, fluocerite and bastn/isite.
    [Show full text]
  • Cafetite, Ca[Ti2o5](H2O): Crystal Structure and Revision of Chemical Formula
    American Mineralogist, Volume 88, pages 424–429, 2003 Cafetite, Ca[Ti2O5](H2O): Crystal structure and revision of chemical formula SERGEY V. K RIVOVICHEV,1,* VICTOR N. YAKOVENCHUK,2 PETER C. BURNS,3 YAKOV A. PAKHOMOVSKY,2 AND YURY P. MENSHIKOV2 1Department of Crystallography, St. Petersburg State University, University Embankment 7/9, St. Petersburg 199034, Russia 2Geological Institute, Kola Science Centre, Russian Academy of Sciences, Fersmana 14, 184200-RU Apatity, Russia 3Department of Civil Engineering and Geological Sciences, University of Notre Dame, Notre Dame, Indiana 46556-0767, U.S.A. ABSTRACT The crystal structure of cafetite, ideally Ca[Ti2O5](H2O), (monoclinic, P21/n, a = 4.9436(15), b = 12.109(4), c = 15.911(5) Å, b = 98.937(5)∞, V = 940.9(5) Å3, Z = 8) has been solved by direct methods and refined to R1 = 0.057 using X-ray diffraction data collected from a crystal pseudo-merohedrally twinned on (001). There are four symmetrically independent Ti cations; each is octahedrally coordi- nated by six O atoms. The coordination polyhedra around the Ti cations are strongly distorted with individual Ti-O bond lengths ranging from 1.743 to 2.223 Å (the average <Ti-O> bond length is 1.98 Å). Two symmetrically independent Ca cations are coordinated by six and eight anions for Ca1 and Ca2, respectively. The structure is based on [Ti2O5] sheets of TiO6 octahedra parallel to (001). The Ca atoms and H2O groups are located between the sheets and link them into a three-dimensional struc- ture. The structural formula of cafetite confirmed by electron microprobe analysis is Ca[Ti2O5](H2O), .
    [Show full text]
  • Moon Minerals a Visual Guide
    Moon Minerals a visual guide A.G. Tindle and M. Anand Preliminaries Section 1 Preface Virtual microscope work at the Open University began in 1993 meteorites, Martian meteorites and most recently over 500 virtual and has culminated in the on-line collection of over 1000 microscopes of Apollo samples. samples available via the virtual microscope website (here). Early days were spent using LEGO robots to automate a rotating microscope stage thanks to the efforts of our colleague Peter Whalley (now deceased). This automation speeded up image capture and allowed us to take the thousands of photographs needed to make sizeable (Earth-based) virtual microscope collections. Virtual microscope methods are ideal for bringing rare and often unique samples to a wide audience so we were not surprised when 10 years ago we were approached by the UK Science and Technology Facilities Council who asked us to prepare a virtual collection of the 12 Moon rocks they loaned out to schools and universities. This would turn out to be one of many collections built using extra-terrestrial material. The major part of our extra-terrestrial work is web-based and we The authors - Mahesh Anand (left) and Andy Tindle (middle) with colleague have build collections of Europlanet meteorites, UK and Irish Peter Whalley (right). Thank you Peter for your pioneering contribution to the Virtual Microscope project. We could not have produced this book without your earlier efforts. 2 Moon Minerals is our latest output. We see it as a companion volume to Moon Rocks. Members of staff
    [Show full text]
  • Occurrence, Alteration Patterns and Compositional Variation of Perovskite in Kimberlites
    975 The Canadian Mineralogist Vol. 38, pp. 975-994 (2000) OCCURRENCE, ALTERATION PATTERNS AND COMPOSITIONAL VARIATION OF PEROVSKITE IN KIMBERLITES ANTON R. CHAKHMOURADIAN§ AND ROGER H. MITCHELL Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada ABSTRACT The present work summarizes a detailed investigation of perovskite from a representative collection of kimberlites, including samples from over forty localities worldwide. The most common modes of occurrence of perovskite in archetypal kimberlites are discrete crystals set in a serpentine–calcite mesostasis, and reaction-induced rims on earlier-crystallized oxide minerals (typically ferroan geikielite or magnesian ilmenite). Perovskite precipitates later than macrocrystal spinel (aluminous magnesian chromite), and nearly simultaneously with “reaction” Fe-rich spinel (sensu stricto), and groundmass spinels belonging to the magnesian ulvöspinel – magnetite series. In most cases, perovskite crystallization ceases prior to the resorption of groundmass spinels and formation of the atoll rim. During the final evolutionary stages, perovskite commonly becomes unstable and reacts with a CO2- rich fluid. Alteration of perovskite in kimberlites involves resorption, cation leaching and replacement by late-stage minerals, typically TiO2, ilmenite, titanite and calcite. Replacement reactions are believed to take place at temperatures below 350°C, 2+ P < 2 kbar, and over a wide range of a(Mg ) values. Perovskite from kimberlites approaches the ideal formula CaTiO3, and normally contains less than 7 mol.% of other end-members, primarily lueshite (NaNbO3), loparite (Na0.5Ce0.5TiO3), and CeFeO3. Evolutionary trends exhibited by perovskite from most localities are relatively insignificant and typically involve a decrease in REE and Th contents toward the rim (normal pattern of zonation).
    [Show full text]
  • Petrology of Nepheline Syenite Pegmatites in the Oslo Rift, Norway: Zr and Ti Mineral Assemblages in Miaskitic and Agpaitic Pegmatites in the Larvik Plutonic Complex
    MINERALOGIA, 44, No 3-4: 61-98, (2013) DOI: 10.2478/mipo-2013-0007 www.Mineralogia.pl MINERALOGICAL SOCIETY OF POLAND POLSKIE TOWARZYSTWO MINERALOGICZNE __________________________________________________________________________________________________________________________ Original paper Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: Zr and Ti mineral assemblages in miaskitic and agpaitic pegmatites in the Larvik Plutonic Complex Tom ANDERSEN1*, Muriel ERAMBERT1, Alf Olav LARSEN2, Rune S. SELBEKK3 1 Department of Geosciences, University of Oslo, PO Box 1047 Blindern, N-0316 Oslo Norway; e-mail: [email protected] 2 Statoil ASA, Hydroveien 67, N-3908 Porsgrunn, Norway 3 Natural History Museum, University of Oslo, Sars gate 1, N-0562 Oslo, Norway * Corresponding author Received: December, 2010 Received in revised form: May 15, 2012 Accepted: June 1, 2012 Available online: November 5, 2012 Abstract. Agpaitic nepheline syenites have complex, Na-Ca-Zr-Ti minerals as the main hosts for zirconium and titanium, rather than zircon and titanite, which are characteristic for miaskitic rocks. The transition from a miaskitic to an agpaitic crystallization regime in silica-undersaturated magma has traditionally been related to increasing peralkalinity of the magma, but halogen and water contents are also important parameters. The Larvik Plutonic Complex (LPC) in the Permian Oslo Rift, Norway consists of intrusions of hypersolvus monzonite (larvikite), nepheline monzonite (lardalite) and nepheline syenite. Pegmatites ranging in composition from miaskitic syenite with or without nepheline to mildly agpaitic nepheline syenite are the latest products of magmatic differentiation in the complex. The pegmatites can be grouped in (at least) four distinct suites from their magmatic Ti and Zr silicate mineral assemblages.
    [Show full text]
  • Chemical Composition and Petrogenetic Implications of Eudialyte-Group Mineral in the Peralkaline Lovozero Complex, Kola Peninsula, Russia
    minerals Article Chemical Composition and Petrogenetic Implications of Eudialyte-Group Mineral in the Peralkaline Lovozero Complex, Kola Peninsula, Russia Lia Kogarko 1,* and Troels F. D. Nielsen 2 1 Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia 2 Geological Survey of Denmark and Greenland, 1350 Copenhagen, Denmark; [email protected] * Correspondence: [email protected] Received: 23 September 2020; Accepted: 16 November 2020; Published: 20 November 2020 Abstract: Lovozero complex, the world’s largest layered peralkaline intrusive complex hosts gigantic deposits of Zr-, Hf-, Nb-, LREE-, and HREE-rich Eudialyte Group of Mineral (EGM). The petrographic relations of EGM change with time and advancing crystallization up from Phase II (differentiated complex) to Phase III (eudialyte complex). EGM is anhedral interstitial in all of Phase II which indicates that EGM nucleated late relative to the main rock-forming and liquidus minerals of Phase II. Saturation in remaining bulk melt with components needed for nucleation of EGM was reached after the crystallization about 85 vol. % of the intrusion. Early euhedral and idiomorphic EGM of Phase III crystalized in a large convective volume of melt together with other liquidus minerals and was affected by layering processes and formation of EGM ore. Consequently, a prerequisite for the formation of the ore deposit is saturation of the alkaline bulk magma with EGM. It follows that the potential for EGM ores in Lovozero is restricted to the parts of the complex that hosts cumulus EGM. Phase II with only anhedral and interstitial EGM is not promising for this type of ore.
    [Show full text]